U.S. Pat. Nos. 4,708,084 and 4,948,095 as well as Ser. No. 07/713,626, are hereby incorporated by reference into this disclosure.
The present invention relates generally to electrically controlled devices for multi-point positioning. The present invention relates more specifically to electrically controlled multi-point positioners which can selectively control a rotating means, thus allowing operator-controlled selection for a number of applications, including the use of a multi-point valve positioner in a water distribution system which is in communication between a reservoir and a lake.
The water distribution systems disclosed in U.S. Pat. Nos. 4,589,441, 4,708,084 and 4,948,095 represent typical prior art apparatus for controlling the flow of water between a livewell and an external water source. These systems are used widely by many manufacturers of sport fishing boats. They achieve various advantages such as the use of a single pump to both fill the livewell and recirculate livewell water through the system's aeration device and the ability, when the boat is running, to automatically prevent loss of livewell water out the drain port, while continuing to draw water from the livewell drain for recirculation and aeration. Further advantages are found in co-pending Ser. No. 07/712,626. This application discloses a remote control valve that will fill, recirculate and drain a livewell/baitwell contained within a fishing boat, utilizing a mechanically actuated push-pull cable means. Valve stem extension means are also utilized in the prior art for mechanical actuation of such control valves. Such mechanically actuated control valve means are very convenient for fishermen, and are now widely used on boats in tournament style fishing.
However, mechanically actuated control valves do suffer from certain disadvantages. For example, as regards the application to fishing boats, mechanical actuation means are expensive to install, requiring considerable time and skilled labor. If not rigged precisely, they can fail to position the valve properly. Also, since most boats are now "foamed" in (i.e., foam is sprayed directly onto the boat, hardening and conforming to the boat surface), push-pull cable control means must be installed at the time of manufacture of the boats. Moreover, this exothermic foam curing process can generate enough heat to cause the control cable plastic jacket to soften, leading to unacceptably high cable friction and actuator force. The foaming process also limits the market for livewell control systems utilizing manually actuated control systems to new boats, since retrofit is impractical.
It would therefore be desireable to provide an inexpensive valve positioner which would eliminate the problems associated with the push-pull control cable disclosed in co-pending Ser. No. 07/713,626, while retaining the advantages disclosed in that application. However, conventional switch contact means, such as magnetic reed switches, electronic proximity switches, mechanical snap-action switches, and optical or conventional rotary mechanical wiper type switches, all require precise alignment for proper valve positioning. Thus, deflections in the sealing glands or o-rings, due to varying loads which can cause rotor wobble, must be prevented in order for these types of switch contact means to function properly; a failure to prevent such deflections could introduce positioning error or failure of the switch "make or break" function. Also, the switch mechanism must be shock resistant since it could sit on the floor of a high speed tournament fishing boat operating for extended periods in rough water.
Further, conventional ball and plug type valves have a variable break-free torque depending on idle time and temperature; reaction loads to such torques are high and require a relatively heavy structure to maintain the precise alignment of parts required for proper valve operation. Variable torques can also cause operating speed variations that can affect positioning accuracy, necessitating higher gear reduction drive systems to eliminate coasting during low torque cycles.